Safety device for elevators



No Model.)

W. B. NICKERSON. SAFETY DEVICE POR BLEVATORS.

Patented Jung 18, 1889.

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W. E. NIGKERSON.

SAFETYDEVICE FOR ELEVATORS.

No. 405,371. Patented Jun@ '18, 1889.

' slowly to the bottom.

UNITED STATES PATENT OFFICE.

IVILLIAM E. NIC-KERSON, OF CAMBRIDGE, MASSACHUSETTS."

SAFETY DEVICE FOR ELEVATOFIS.

SPECIFICATION forming part of Letters Patent No. 405,371, dated J une18, 18189. Application tiled Iauuary 1'7, 1889. Serial No. 296,611. (Nomodel.) Y

To all whom it may concern.-

Be it known that I, WILLIAM E. NICKER- sON, of Cambridge, in the countyof Middlesex and State of Massachusetts, have invented certain new anduseful Improvements in Elevator Appliances, of which the following,taken in connection with the accompanying drawings, is a specification.

My invention consists in applying to elevators in which aspeed-retarding device is used a gripping mechanism operated by andcoacting with the retarding device to regulate the speed of the carwhenever it shall become too great from any cause-such, for example, asthe breaking of the hoisting apparatusand to allow the car to descendThis I attain by the mechanism shown in the accompanying drawings, inwhich- Figure l shows in front elevation an elevator-carriage, itsguides, and the hoistingropes, together with their sheaves, theretarding-ropes and drum not being shown in this figure. Fig. 2 shows inside elevation an elevator-carriage, one of the retarding-ropes, and itsdrum, together with one of the hoisting-ropes and its sheaves. Fig. 3 isa plan showing the parts of my invention that relate to the grippingdevice. Fig. 4 is an elevation of the same. Fig. 5 is a detail of thesame.

In the drawings I have shown such parts` only as relate particularly tomy invention, details not connected with my present device beingomitted. The carriage of the elevator is represented by A, Figs. l, 2,3, and 4, and the guides and posts byB B BB,Figs. l, 3, and 4.

Attached to the top of the elevator-carriage A, I have a strong housingA2, in which I have two sets of sheaves C5 C5 and H Il. (See Fig. 3.) Ialso have attached to the top of the elevator-carriage two grippingdevices C C2 C C2-one for each of the guides B B. (See Fig. 4.) Thegripping devices are constructed as follows: C2, Fig. 4, is a fixed armirmly bolted to the top of the elevator-carriage, as shown, and C is apivot-ed arm attached by the pivotal bolt C. The jaws c c of thegripping device slide normally free on the guides B but are arranged tofirmly grip the guides when from any cause the carriage is descendingtoo fast, as will be explained. Each of the pivoted arms of the grippingdevice has lateral extensions C3 C4, (see Fig. 5,) that extend under thesheaves C5 H', respectively, and are connected as follows: C3 to thehoisting-rope D, (see Figs. l and 5,) and C4 to the retardin g-rope II.The retarding-ropes I-I pass around and are attached to the speedregulatin g drum H2, Fig. 2,which,together with its connected devices, isfully described in Letters Paten't granted to me February l5, 1887, No.357,938. The counteracting-rope K passes under the sheave K', Fig. 2,and then to the bottom of the elevator-carriage A, to

which it is fastened by the swivel-joint K3.'

The counteracting-rope K and its connected parts is fully described inLetters Patent granted to me December 1S, 1S8S,No. 394,600. Thehoisting-rope I) passes over the sheave D and under the sheave D2 to thehoistingmachine.

From the above it will be understood that when the hoisting andretarding devices are all working in good order and the carriage ismoving at or within its normal rate of speed, either up or down, t-hegripping device C C2 will not operate to interfere in any manner withthe movement of the elevator-carriage, for the reason that under normalconditions the strain on the hoisting-rope I) is much greater than thaton the retarding-rope, so that the gripping device will be heldinoperative; but if the speed of the descending car increases much abovethe normal rate th en the increased resistance of the retarding device,acting against the retention of the hoisting-rope, will overcomer it andforce the gripping device into action. Now we have both the grippingdevice and the retarder acting to check the speed of the car. Thiscombined action will soon bring the speed of the car to a rate at whichits weight is equivalent to said combined retarding action. Thisnecessitates a uniform rate of descent, for if the car were to go fasterthen the increased resistance of the retarder, acting through theretarding-rope, would check it by the gripping device, and if it goesslower then the tension on the retarding-rope is diminished and thegripping device acts less strongly, allowing the rate of speed toincrease unt-il the weight of the car again balances the com- ICO binedretarding action. In brief, my mechanism constitutes a device by whichsafety is attained by a regulation of the speed of descent instead of bystopping` the car.

One advantage of my combination is that the restraining action of theretarder is assisted by the gripping device, thus allowing the use of aretarder of comparatively small proportions.

I claiml l. In an elevator, the combination of the carriage A,hoisting-rope D, retarding-rope H, and its retarder, adapted to resistmore strongly as the speed of the descending car increases, with a gripdevice to which the hoisting-rope D and retarding-rope H are bothattached, but pulling in opposite directions, the hoisting-rope Dtending to loosen the grip'and the retarding-rope H tending to set it,whereby an undue increase in the velocity of the descending carriagewill cause the increased resistance of the retarder through the rope Hto overcome the tension of the hoisting-rope D and operate the grip,substantially as and for the purpose set forth.

2. In an elevator, the combination of the carriage A, guide B', thegripping device consisting' of the fixed arm C2 and pivoted gripping-armC, having attached to it and being held inoperative by the hoisting-ropeD, With the retarding-rope H, also attached to the arm C, but pulling inthe opposite direction from the rope D, and a retarder, all opera tingtogether substantially as and for the purpose set forth.

WILLIAM E. NICKERSON.

